George Grätzer, Member of the Canadian Academy of Sciences and Foreign Member of the Hungarian Academy of Sciences, is the author of 26 books in five languages and about 270 articles, most of them on his research in lattice theory.Friedrich Wehrung is professor at the University of Caen and an associate editor for Algebra Universalis, a mathematical journal devoted to universal algebra and lattice theory. He is the author of numerous publications in the field and wrote an appendix to the second edition of Grätzer's General Lattice Theory.

• Varieties of Lattices.- Free and Finitely Presented Lattices.- Classes of Semidistributive Lattices.- Lattices of Algebraic Subsets and Implicational Classes.- Convex Geometries.- Bases of Closure Systems.- Permutohedra and Associahedra.- Generalizations of the Permutohedron.- Lattice Theory of the Poset of Regions.- Finite Coxeter Groups and the Weak Order.

George Grätzer, Member of the Canadian Academy of Sciences and Foreign Member of the Hungarian Academy of Sciences, is the author of 26 books in five languages and about 270 articles, most of them on his research in lattice theory.Friedrich Wehrung is professor at the University of Caen and an associate editor for Algebra Universalis, a mathematical journal devoted to universal algebra and lattice theory. He is the author of numerous publications in the field and wrote an appendix to the second edition of Grätzer's General Lattice Theory.

• Varieties of Lattices.- Free and Finitely Presented Lattices.- Classes of Semidistributive Lattices.- Lattices of Algebraic Subsets and Implicational Classes.- Convex Geometries.- Bases of Closure Systems.- Permutohedra and Associahedra.- Generalizations of the Permutohedron.- Lattice Theory of the Poset of Regions.- Finite Coxeter Groups and the Weak Order.

George Grätzer, Member of the Canadian Academy of Sciences and Foreign Member of the Hungarian Academy of Sciences, is the author of 26 books in five languages and about 270 articles, most of them on his research in lattice theory.Friedrich Wehrung is professor at the University of Caen and an associate editor for Algebra Universalis, a mathematical journal devoted to universal algebra and lattice theory. He is the author of numerous publications in the field and wrote an appendix to the second edition of Grätzer's General Lattice Theory.

• Varieties of Lattices.- Free and Finitely Presented Lattices.- Classes of Semidistributive Lattices.- Lattices of Algebraic Subsets and Implicational Classes.- Convex Geometries.- Bases of Closure Systems.- Permutohedra and Associahedra.- Generalizations of the Permutohedron.- Lattice Theory of the Poset of Regions.- Finite Coxeter Groups and the Weak Order.